diff --git a/lisp/x86-validate.h b/lisp/x86-validate.h
index e71dea8de2ef44f3acff486f7996dd2e1646be2f..b94387021bc8436537b3350988b92b473e96f1f9 100644
--- a/lisp/x86-validate.h
+++ b/lisp/x86-validate.h
@@ -24,6 +24,7 @@
  */
 #define CONTROL_STACK_START	(0x50000000)
 #define CONTROL_STACK_SIZE	(0x00100000)
+#define CONTROL_STACK_END	(CONTROL_STACK_START + CONTROL_STACK_SIZE)
 
 #define BINDING_STACK_START	(0x60000000)
 #define BINDING_STACK_SIZE	(0x00100000)